a. Field of the Invention
The present invention relates to polycarbonate resin compositions comprising a polycarbonate resin, and at least two colorants with thermal resistance and satisfactory blueing effect.
B. Description of the Prior Art
At present, polycarbonates are manufactured by reacting phosgene and a dihydroxy compound, or by an ester exchange method using a diphenylcarbonate and a dihydroxy compound. As the dihydroxy compound in these reactions, an aromatic dihydroxy compound is commonly used.
A colorless transparent polycarbonate using such an aromatic dihydroxy compound as a raw material is tinged with yellow. Therefore, when said polycarbonate is applied to a use requiring transparency, such as the treatment called blueing, the method of coloring with an extremely thin blue-purple color, has been accomplished.
Heretofore, an organic dye of a single color has been used conventionally as a colorant in this treatment. But it cannot resist molding temperatures used with polycarbonate resins (i.e., 260.degree.-320.degree.C.), and its color fades at the time of molding. Such being the case, this colorant could not attain the desired purpose in most cases.
It is an object of the present invention to obtain a polycarbonate resin having remarkably improved transparency by means of adding colorants to a polycarbonate resin.